March 3-March 4 - A total lunar eclipse occurs, visible in some parts of the Americas and Asia, and all of Europe and Africa.
March 19 - A partial solar eclipse occurs, visible in Asia.
April 10 - Spectroscopic analysis of HD 209458 b, an extrasolar planet, provides the first evidence of atmospheric water vapor beyond the Solar System.
April 25 - Gliese 581 c is discovered and identified as a potentially habitable Earth-like extrasolar planet in the constellation Libra.
June 5 - NASA's MESSENGER spacecraft makes its second flyby of Venus en route to Mercury.
August 28 - A total lunar eclipse occurs, visible in some parts of the Americas and Asia, and all of Australasia and the Pacific Ocean.
September 11 - A partial solar eclipse occurs, visible in southern areas of South America.
September 27 - NASA's Dawn spacecraft is launched.
October 24 - Comet 17P/Holmes suddenly brightens from 17 to about 2.8 magnitude.

Computing

April 27 - US researchers have simulated half a virtual mouse brain on a supercomputer.[1]

Genetic engineering

January 14 - Scientists at the Roslin Institute announce they have genetically engineered chickens which can lay eggs with the ability to fight cancer.[2]

Philosophy of science

Publication of Nassim Nicholas Taleb's book The Black Swan: the Impact of the Highly Improbable, discussing the "Black swan theory"

Chemistry to Gerhard Ertl "for his studies of chemical processes on solid surfaces"

Physiology or Medicine to Mario R. Capecchi, Sir Martin J. Evans and Oliver Smithies "for their discoveries of principles for introducing specific gene modifications in mice by the use of embryonic stem cells"